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40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
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| 40m Log |
Not logged in |
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 Thu Jan 4 12:46:27 2018, gautam, Update, ALS, Fiber ALS assay 
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 Thu Jan 11 14:22:40 2018, gautam, Update, ALS, Fiber ALS assay
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Thu Jan 11 20:51:20 2018, gautam, Update, ALS, Fiber ALS assay
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Tue Jan 16 21:50:53 2018, gautam, Update, ALS, Fiber ALS assay
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Thu Jan 18 00:35:00 2018, gautam, Update, ALS, Fiber ALS assay
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Fri Jan 19 11:34:21 2018, gautam, Update, ALS, Fiber ALS assay
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Fri Jan 19 23:04:11 2018, gautam, Update, ALS, Fiber ALS assay
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Wed Jan 24 00:33:31 2018, gautam, Update, ALS, Fiber ALS assay
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Wed Jan 24 10:45:14 2018, gautam, Update, ALS, Fiber ALS assay
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Thu Jan 25 23:59:14 2018, gautam, Update, ALS, Fiber ALS assay
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Fri Jan 26 20:03:09 2018, gautam, Update, ALS, Fiber ALS assay
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Wed Jan 31 15:45:22 2018, gautam, Update, ALS, Fiber ALS assay
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Wed Jan 31 16:29:42 2018, gautam, Update, ALS, Modulation depths
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Wed Jan 31 16:33:53 2018, gautam, Update, ALS, ALS electronics at LSC rack
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Wed Jan 31 22:32:11 2018, gautam, Update, ALS, ALS signal chain + power budget
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Thu Feb 1 01:24:56 2018, gautam, Update, ALS, D0902745 revamp underway
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Fri Feb 2 00:26:34 2018, gautam, Update, ALS, D0902745 revamp underway
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Fri Feb 2 13:16:55 2018, gautam, Update, ALS, ALS signals whitening switching
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Mon Feb 5 14:11:01 2018, gautam, Update, ALS, Huge harmonics in ALS channels
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Mon Feb 5 22:57:28 2018, gautam, Update, ALS, Huge harmonics in ALS channels
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Tue Feb 6 11:13:26 2018, gautam, Update, ALS, Possible source of ground loop identified
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Tue Feb 6 22:55:51 2018, gautam, Update, ALS, Possible source of ground loop identified
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Thu Feb 8 00:33:20 2018, gautam, Update, ALS, D990694 characterization / THD measurement plan
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Thu Feb 8 01:27:16 2018, Koji, Update, ALS, D990694 characterization / THD measurement plan
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Fri Feb 9 13:37:44 2018, gautam, Update, ALS, THD measurement trial
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Thu Feb 8 12:00:09 2018, gautam, Update, ALS, D990694 is NOT differential receiving
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Thu Feb 8 13:13:14 2018, gautam, Update, ALS, D990694 pulled out
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Thu Feb 8 18:10:36 2018, gautam, Update, ALS, D990694 pulled out
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Wed Feb 7 15:51:15 2018, gautam, Update, ALS, D0902745 revamp complete
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Fri Feb 16 01:34:40 2018, gautam, Update, ALS, D0902745 in-situ testing
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Tue Feb 20 23:08:27 2018, gautam, Update, ALS, D0902745 in-situ testing
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Thu Feb 22 00:09:11 2018, gautam, Update, ALS, D0902745 in-situ testing
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Sun Feb 25 00:03:12 2018, gautam, Update, ALS, Daughter board prototyping
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Mon Feb 26 20:55:56 2018, rana, Update, ALS, Daughter board prototyping
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Tue Feb 27 21:10:45 2018, gautam, Update, ALS, Daughter board testing
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Wed Feb 28 19:13:25 2018, gautam, Update, ALS, ADC test for differential receiving in c1lsc
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Fri Mar 2 01:45:06 2018, gautam, Update, ALS, new look ALS electronics
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Mon Mar 5 17:27:34 2018, gautam, Update, ALS, new look ALS electronics - characterization
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Thu Mar 8 00:40:25 2018, gautam, Update, ALS, new look ALS electronics - characterization
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Thu Mar 8 19:38:37 2018, gautam, Update, ALS, digital unwhitening of daughter board
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Thu Mar 8 23:50:27 2018, gautam, Update, ALS, First look at new ALS electronics
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Fri Mar 9 01:07:01 2018, gautam, Update, ALS, First look at new ALS electronics
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Mon Mar 12 22:08:31 2018, gautam, Update, ALS, Noisy POX
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Mon Mar 12 23:57:31 2018, gautam, Update, ALS, Noisy POX
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Mon Mar 19 15:02:29 2018, gautam, Update, ALS, Noisy MC sensing
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Thu Feb 1 15:31:12 2018, gautam, Update, ALS, ALS signal chain + power budget
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Wed Feb 7 10:16:26 2018, gautam, Update, ALS, ALS signal chain + power budget
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Thu Jan 25 13:18:41 2018, gautam, Update, ALS, Fiber ALS assay
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Message ID: 13600
Entry time: Fri Feb 2 13:16:55 2018
In reply to: 13599
Reply to this: 13606
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| Author: |
gautam |
| Type: |
Update |
| Category: |
ALS |
| Subject: |
ALS signals whitening switching |
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While setting up for this measurement, I noticed something odd with the whitening switching for the ALS channels. For the usual LSC channels, the whitening is set up such that switching FM1 on the MEDM screen changes a BIO bit which then enables/disables the analog whitening stage. But this feature doesn't seem to be working for the ALS channels - I terminated all 4 channels at the LSC rack, and measured the spectrum of the IN1 signals with DTT in the two settings, such that I expect to see a difference in the spectra if the whitening is enabled or disabled - FM1 enabled (expected analog whitening to be engaged) and FM1 disabled (expected analog whitening to be bypassed). But I see no difference in the spectra. I confirmed that the BIO bit switching is happening at least on the software level (i.e. the bit indicator MEDM screens indicate state toggling when FM1 is ON/OFF). But I don't know if something is amiss in the signal chain, especially since we are using Hardware channels that were previously used for AS_165 and POP_55 signals.
Is the whitening shape such that we expect the terminated noise level to be below ADC Noise even when the whitening is engaged? I just checked the shape of the de-whitening filter, and it has -40dB gain above 150Hz, so the inverse shape should have +40dB gain.
| Quote: |
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I will now proceed to the next piece (#3?) of this puzzle, which is to understand how the D990694 which receives the signals from this unit reacts to the expected DC voltage level of ~4Vpp
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gautam 2.15pm: This was a FALSE ALARM, with the inputs terminated, the electronics noise really is that low such that it is buried under ADC noise even with +40dB gain. I cranked up the flat whitening gain from 0dB to 45dB for the X channels (but left the Y channels at 0dB). Attachment #2 is the comparison. Looks like the switching works just fine. |
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